The present invention relates to an apparatus according to the preamble to appended claim 1.
Prior art apparatuses according to the foregoing paragraph are applicable in warping machines for the textile industry and a warping machine or warper may be provided with a bobbin frame which can be 20-30 m in length, extend from floor to ceiling, and have a left-hand frame and a right-hand frame which are identical but are mirror-reversed. The frames are often placed in V-shape with the warp wrapping at the apex of the V. On each vertical post in the frame, there may be 8-10 thread bobbins in the vertical direction, and the distance between the posts may be 500 mm, which implies 16-20 threads per meter of bobbin frame, for which reason a 20 m long frame displays 20xc3x9716-20 threads (320-400 thread m each frame and, consequently, 640-800 threads in a frame). When stationary, the threads must be braked in order to avoid tearing off the threads from bobbins because of the weight of the threads. The most distal threads hang freely approx. 20 meters and it is not desirable to provide any braking support substantially because the braking would, in such an event, vary depending upon from how far away the threads come. At the start of the warper, the brake is in the engaged or braking position and when the warper has reached a certain speed, the brake is switched to the disengaged position. Thereafter, the warper increases speed to a thread speed as high as 250 kph. If anything happens, e.g. a break in a thread, the warper must be stopped very rapidly, and in order to prevent continued unreeling of the threads from the bobbins, the thread brakes must be switched to the engaged, braking position very rapidly. In prior art constructions, levers are provided all of the way from the end of each frame to each post where the movement of the levers is to be angled down on the post to each thread brake (8-10 in number). There are also designs and constructions employing a pneumatic piston for each post. The drawbacks inherent in these prior art constructions are obvious and serious. Above all, large mechanical masses are to be switched, and in the case of the pneumatic arrangement, long air hoses are also required which are to be filled. In addition to considerable mechanical complexity, the brakes operate extremely slowly, which is a major drawback.
The task forming the basis of the present invention is to obviate or at least reduce the drawbacks in prior art brake constructions in order to facilitate and improve the application of the brake apparatus according to the present invention, principally in warping machines.
This task is solved according to the present invention in the apparatus disclosed by way of introduction in that this is given the characterising features as set forth in appended Claim 1.
The present invention realises an apparatus for braking a thread in, for example, a warping machine possessing many advantages vis-à-vis constructions according to prior art technology. Such advantages are, for instance, more rapid engagement and disengagement, a fewer number of parts, simple adaptability to frames of different distribution, each post can be finished at the works, in the use of bistable magnets as driving unit only one pulse is required for switching between braking position and disengaged position, and in between no energy consumption is required, with electric energy storing capacitors for each brake driving unit it is sufficient to use a small mains unit for all the brake driving units, the charge in the capacitor may be sufficient for both engagement and disengagement of the brake, each unit is readily replaceable, no adjustment of mechanical parts, a single operating panel for controlling all brakes and units, easy to retrofit extant bobbin frames and possibly change the distribution between the posts, the apparatus can be given an extremely streamlined design without levers, air cylinders and hoses, etc.